1. Field of the Invention
The present invention relates generally to a capacity control apparatus for variable capacity-type compressors for use in automotive air conditioning systems. In particulars the present invention relates to a capacity control apparatus that may directly control an actual discharge capacity of variable capacity-type compressors, and which may be used to control refrigeration circuits in automotive air conditioning systems
2. Description of Related Art
A capacity control apparatus for a variable capacity-type compressor is described in, for example, Japanese (Unexamined) Patent Publication No. 64-073178. In this known variable capacity-type compressor, a discharge capacity of the compressor is regulated by a control means, e.g., an electromagnetic valve or the like. The control means regulates the discharge capacity of the compressor based on a measured physical characteristic related to cooling efficiency of a refrigeration circuit, e.g., a pressure or a temperature of a refrigerant.
In this known variable capacity-type compressor, the actual discharge capacity of the compressor may be adjusted, as needed. For example, the discharge capacity of the compressor may be adjusted in response to a condition of the refrigeration circuit, e.g., to an increased air conditioning load on the refrigeration circuit. Moreover, actual discharge capacity of the compressor may be adjusted toward a predetermined discharge capacity target of the compressor. For example, a target discharge capacity value of the compressor may be established, and the actual discharge capacity may be adjusted toward the target discharge capacity value. Therefore, in such known variable capacity type compressors, in which an engine of a vehicle may drive the compressor, a load fluctuation of the compressor may not correspond to a load of the engine. As a result, efficient operation of the compressor may not be achieved.
In order to improve the efficiency of such compressors, such compressors may include a discharge capacity control apparatus for a variable capacity-type compressor, as described in Japanese Patent No. 3060676. In this known variable capacity-type compressor, a torque detection device is positioned on the compressor to measure a torque of a drive of the compressor, e.g., a torque of a drive shaft of a compressor or the like. An output of a vehicle engine then may be adjusted based on the measured value of torque driving the compressor.
Nevertheless, in known variable capacity-type compressors having such a torque detection device, the compressor load is measured, and this measurement is used to control the air conditioning system of the vehicle. Nevertheless, the discharge capacity of the compressor is not adjusted toward a predetermined target discharge value of the compressor.
Therefore, a need has arisen for a discharge capacity, control apparatus for variable capacity-type compressors that regulates operation of the compressor, so that the compressor discharge capacity approaches or reaches a discharge capacity target value.
According to an embodiment of the present invention, an apparatus for controlling compressor discharge capacity comprises a variable capacity compressor, a capacity adjustment device, a signal processing device, a capacity setting device, and a signal comparing device. The capacity adjustment device regulates a discharge capacity of the variable capacity compressor. The signal processing device receives a signal corresponding to a discharge capacity of the variable capacity compressor. The capacity setting device sets a first discharge capacity target value for the variable capacity compressor. The signal comparing device compares the discharge capacity signal to the first discharge capacity target value and second an activation signal to the capacity adjustment device, such that the discharge capacity signal approaches the first discharge capacity target value.
In another embodiment of the invention, an apparatus for controlling compressor discharge capacity comprises a variable capacity compressor, a capacity adjustment device, a signal processing device, a capacity setting device, a first signal comparing device, a detection device a pressure setting device, and a second signal comparing device. The capacity adjustment device regulates a discharge capacity of the variable capacity compressor. The signal processing device receives a signal corresponding to a discharge capacity of said variable capacity compressor. The capacity setting device sets a first discharge capacity target value of the variable capacity compressor. The first signal comparing device compares the discharge capacity signal to the first discharge capacity target value and sends a first activation signal to the capacity adjustment device, such that the discharge capacity signal reaches the first discharge capacity value. The detection device detects a first pressure value in a refrigeration circuit including the variable capacity compressor. A pressure setting device sets a second pressure target value. A second signal comparing device compares the first pressure value with the second pressure target value and sends an activation signal to the capacity adjustment device, such that the first pressure value approaches the second pressure target value. The compressor discharge capacity controlling apparatus may comprise a switching device that selectively connects the first signal comparing device and the second signal comparing device to the capacity adjustment device.
In another embodiment of the invention, an apparatus for controlling compressor discharge capacity comprises a variable capacity compressor, a capacity adjustment device, a signal processing device, a capacity setting device, a first signal comparing device, a detection device, a temperature setting device, and a second signal comparing device. The capacity adjustment device regulates a discharge capacity of the variable capacity compressor. The signal processing device receives a signal corresponding to a discharge capacity of said variable capacity compressor. The capacity setting device sets a first discharge capacity target value of the variable capacity compressor. The first signal comparing device compares the discharge capacity signal to the first discharge capacity target value and sends an activation signal to the capacity adjustment device, such that the discharge capacity signal reaches the first discharge capacity value. The detection device detects a first temperature value in a refrigeration circuit including the variable capacity compressor. A temperature setting device sets a second temperature target value. A second signal comparing device compares the first temperature value with the second temperature target value and sends an activation signal to the capacity adjustment device, such that the first temperature value approaches the second temperature target value. The compressor discharge capacity controlling apparatus may comprise a switching device that selectively connects the first signal comparing device and the second signal comparing device to the capacity adjustment device.
According to a further embodiment of the invention, a method of controlling a discharge capacity of a variable capacity compressor connected to a refrigeration circuit comprises the following steps. A first discharge capacity value of the variable capacity compressor is set. A discharge capacity of the variable capacity compressor is detected. The discharge capacity value is compared with the first discharge capacity target value. The discharge capacity of the variable capacity compressor is adjusted, such that the discharge capacity value approaches the first discharge capacity value.
Other objects, features, and advantages of embodiments of this invention will be apparent to persons of ordinary skill in the art from the following detailed description of the invention and the accompanying drawings.